Colin Briggs (Clive Owen) is a man who has given up on life. Near the end of a long sentence for murder, Colin meets Fergus Wilks (David Kelly), an eccentric "lifer" who gives Colin an unwanted packet of seeds as a Christmas present. He begrudgingly plants the seeds in Edgefield's hard, infertile soil and, much to both men's surprise; the seeds flourish along with the two men's friendship. When the prison garden attracts the attention of flamboyant gardening expert, Georgina Woodhouse (Helen Mirren), she offers to sponsor the inmates in their first garden show. As a result of gardening, Colin gains a renewed lease on life, a newly found love for Georgina's daughter and a chance to compete at the Hampton Court Palace Flower Show--the largest outdoor garden event in the world.